British citizens fleeing the chaos engulfing Libya finally began arriving back in the UK reporting "mass hysteria" at Tripoli airport with as many as 10,000 people fighting to get out.

A plane chartered by oil company BP touched down at Gatwick at 7.15am carrying 78 passengers and was expected to be followed by a second aircraft chartered by the Foreign Office that was stuck at Gatwick for most of Wednesday and arrived in Tripoli in the early hours of Thursday.

It flew to Malta with 132 British passengers and picked up a further 51 who had arrived on an RAF Hercules. A second BP-chartered plane was due to fly back tonight with 26 oil workers.

At Gatwick Helena Sheehan, 66, said she had just experienced "some of the worst hours of her life".

"Libya is descending into hell," she said, and described the atmosphere in the airport – where thousands of people, mainly Arabs, were trying to get home to their own countries – as "horrendous".

The airport was "a zoo", said Ewan Black, an IT support worker for an oil company who returned on the same flight.

"I lost all my luggage," he said. "It's literally bodies climbing over bodies to get to the door. I was on my knees at one stage and so was my colleague and it was actually one of the Libyan police who grabbed my arm when I showed him my passport and pulled me in and I pulled the other guy in as well."

The Foreign Office said that the Navy frigate HMS Cumberland had finally left Benghazi following a delay due to bad weather.

It has 200 people aboard from 10 nationalities including 68 Britons. It is sailing to Valletta in Malta, adding to the influx of thousands of foreign nationals on to the Mediterranean island.

David Moore, a surveyor from High Wycombe was working on a new terminal at Benghazi airport when the construction camp was looted and the airstrip bombed by Mig fighters. He was among those who fled to the port to board the warship.

British citizens took whatever route out of Libya they could following delays by the UK government in sending planes and ships. A reported 26 British people left Benghazi aboard a Turkish ferry, while 42 British nationals boarded a US ferry in Tripoli which was stranded in the harbour due to eight-metre swells.

"Unfortunately, as we've all been through customs and have the export stamp in our passports, they're not letting us back into Libya, despite the fact that British planes are regularly taking off from the airport," said Rob Tattersall, an English teacher, by email to a colleague. "Please raise a glass of something nice to us. Our thoughts are with the Libyan people."

His fellow teacher, Emma Wilkes, 24, told her mother, Paula McEwan, that she felt like a sitting duck. "She is worried the boat may be a target," said McEwan. "You don't know what Gaddafi might do. He seems completely unhinged and might decide attacking a US boat is a good idea."

Bryan Richards, a British oil worker, hitched a ride on a Polish flight to Warsaw that had spare seats. He said the atmosphere at Tripoli airport was "hairy, very, very hairy".

Security guards had fired over the heads of people in an attempt to control the crowds, he said. The terminal was crowded with people from Tunisia, Algeria and Egypt, who did not have passports or tickets but were desperate to leave.

"They just came to the airport and camped. They turned a normal docile international airport into a seething mass of people and luggage and you couldn't move anywhere."

Fights broke out at check-in desks between passengers scrambling to leave, and also with security staff.

The Guardian has learned that the three planes the government has chartered are costing around £80,000 each. Crews are carrying tens of thousands of dollars in cash in order to pay airport fees in Libya. The Foreign Office's decision to try to use civilian rather than military planes in the first instance appears to have slowed down the response.

Air Partner, the broker of the plane which was stuck at Gatwick for 10 hours on Wednesday with a minor technical fault, was unable to find an insured alternative aircraft and crew willing to fly into Libyan airspace, where communications with air traffic control have become intermittent.

"Libya is in a state of chaos, all normal communications and many aviation practices have broken down," said Mark Briffa, chief executive of Air Partner. "This has created a highly challenging and sensitive situation, which has slowed the possible rate of evacuations."

The government's response is run by the consular crisis group, a standing Foreign Office directorate overseen by senior civil servant, James Bevan who is in regular contact with William Hague, the foreign secretary.

The crisis group has assembled 50 people in the FCO headquarters, up to 20 of whom are manning the emergency hotline. It includes secondees from the Ministry of Defence and the Department for International Development and the crisis group is managing the evacuation transport by boat and plane as well as logging the location, name and passport numbers of British citizens who call in on a database. It also organises the FCO's rapid deployment teams who have been sent to Libya to provide consular assistance.